1. Field of the Disclosure
The disclosure relates to a vacuum-pump rotor, in particular a rotor for a turbomolecular vacuum pump.
2. Discussion of the Background Art
Vacuum pumps, such as e.g. turbomolecular pumps, comprise a rotor arranged on a rotor shaft. The rotor shaft is driven by an electric motor. The blades of the rotor cooperate with stator discs which usually are fixed in a pump housing. In fast-rotating rotors as used particularly in turbomolecular pumps, it is known to produce rotors from aluminum, steel or corresponding alloys. For obtaining a high vacuum of particularly less than 10−4 mbar, the rotors have to be operated at high rotational speeds. When using rotors of steel, aluminum or the like, a limiting factor resides in the tip speed of the rotor blades, i.e. the tangential speed occurring at the blade tips. With known rotors, a tip speed of 400 m/s can be obtained. A problem in this regard exists when light gases such as e.g. helium or hydrogen are to be conveyed because these have a high thermal speed and, for conveyance, will require a high rotational speed of the rotors, i.e. particularly a high tip speed.
It is an object of the disclosure to provide a vacuum-pump rotor which is adapted to reach a high tip speed.